[Waterproof ABS Material] The RFID key tag is made of high-quality ABS material. The shell is strong and durable with good waterproof, shockproof, and anti-corrosion performance, allowing reliable use in various environments. After multiple manufacturing processes, product quality is ensured. Available in red and blue colors for added choice. [Comes with a Portable Key Ring] Each tag includes a key ring, enabling easy attachment to keys and other items for convenient use and loss prevention. The key tag measures 3.3 x 2.9 x 0.6 cm, making it compact and portable. It can be easily stored in pockets or backpacks. Its rounded shape enhances usability for daily applications. [TK4100 Chip] The RFID sensor ID card uses the TK4100 chip with a working frequency of 125 kHz, compatible with standard ID access control devices. Each chip has a unique ID number permanently stored and printed on the back of the tag for security identification. [Read Only & Easy to Read] The chip is read-only and cannot be rewritten or programmed. It does not support UHF or encrypted formats such as Mifare, Radio, Cobra, APCiK, Indala, Isonas, or similar systems. This waterproof RFID key tag works with 125 kHz card readers with a reading distance of 0–10 cm. [Good Helper for Access Control System] This RFID key tag is suitable for various access control applications including door entry systems, hotel locks, employee attendance, school campus access, identity verification, parking access, and timekeeping systems. It can be used in any location requiring access management such as offices, homes, schools, and residential communities. Support: Read Only, Not Writable Working Frequency: 125 kHz Size: 29 x 33 x 6 mm Material: ABS Color: Blue, Red Package Contents: 50 x 125 kHz RFID Card Tags Note: Light and display settings may cause slight color variations between the image and the actual item. Measurement allows an error of +/- 1–3 cm.